﻿// Copyright 2004-2011 Castle Project - http://www.castleproject.org/
// 
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// 
//     http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#region 导入名称空间

using System;
using System.Diagnostics;
using System.Reflection;
using LightWork.DynamicProxy.Generators;
using LightWork.DynamicProxy.Generators.Emitters;
using LightWork.DynamicProxy.Generators.Emitters.SimpleAST;
using LightWork.DynamicProxy.Tokens;

#endregion

namespace LightWork.DynamicProxy.Contributors
{
    public class InvocationWithGenericDelegateContributor : IInvocationCreationContributor
    {
        private readonly Type delegateType;
        private readonly MetaMethod method;
        private readonly Reference targetReference;

        public InvocationWithGenericDelegateContributor(Type delegateType, MetaMethod method, Reference targetReference)
        {
            Debug.Assert(delegateType.IsGenericType, "delegateType.IsGenericType");
            this.delegateType = delegateType;
            this.method = method;
            this.targetReference = targetReference;
        }

        public ConstructorEmitter CreateConstructor(ArgumentReference[] baseCtorArguments,
            AbstractTypeEmitter invocation)
        {
            return invocation.CreateConstructor(baseCtorArguments);
        }

        public MethodInfo GetCallbackMethod()
        {
            return delegateType.GetMethod("Invoke");
        }

        public MethodInvocationExpression GetCallbackMethodInvocation(AbstractTypeEmitter invocation, Expression[] args,
            Reference targetField,
            MethodEmitter invokeMethodOnTarget)
        {
            var @delegate = GetDelegate(invocation, invokeMethodOnTarget);
            return new MethodInvocationExpression(@delegate, GetCallbackMethod(), args);
        }

        public Expression[] GetConstructorInvocationArguments(Expression[] arguments, ClassEmitter proxy)
        {
            return arguments;
        }

        private Reference GetDelegate(AbstractTypeEmitter invocation, MethodEmitter invokeMethodOnTarget)
        {
            var closedDelegateType = delegateType.MakeGenericType(invocation.GenericTypeParams);
            var localReference = invokeMethodOnTarget.CodeBuilder.DeclareLocal(closedDelegateType);
            var closedMethodOnTarget = method.MethodOnTarget.MakeGenericMethod(invocation.GenericTypeParams);
            var localTarget = new ReferenceExpression(targetReference);
            invokeMethodOnTarget.CodeBuilder.AddStatement(
                SetDelegate(localReference, localTarget, closedDelegateType, closedMethodOnTarget));
            return localReference;
        }

        private AssignStatement SetDelegate(LocalReference localDelegate, ReferenceExpression localTarget,
            Type closedDelegateType, MethodInfo closedMethodOnTarget)
        {
            var delegateCreateDelegate = new MethodInvocationExpression(
                null,
                DelegateMethods.CreateDelegate,
                new TypeTokenExpression(closedDelegateType),
                localTarget,
                new MethodTokenExpression(closedMethodOnTarget));
            return new AssignStatement(localDelegate,
                new ConvertExpression(closedDelegateType, delegateCreateDelegate));
        }
    }
}